Himawari-8 Infrared Window (10.4 µm) images (above) showed Super Typhoon Mangkhut making landfall as a Category 5 intensity storm over the far northern portion of Luzon in the Philippines just after 17 UTC on 14 September 2018 (1 am local time on 15 September). The eye quickly deteriorated and became cloud-filled after moving inland.

The MIMIC-TC morphed microwave product (below) indicated that Mangkhut was in the process of completing an eyewall replacement cycle shortly before making landfall.

westernMIMIC-TC morphed microwave product [click to enlarge]Mangkhut moved over waters of the western Philippine Sea having high values of Ocean Heat Content and Sea Surface Temperature during the final day preceding landfall (below).

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GOES-8 Visible (0.65 µm) images (above) showed the cloud features — including spiral banding and a cloud-free core resembling an eye — associated with a deepening area of low pressure over Lake Huron (surface analyses) on 14 September 1996. This storm acquired some characteristics of a tropical cyclone, being referred to in the literature as “Hurricane Huron“.

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A toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (above) showed Category 2 Hurricane Florence off the coast of North Carolina at 0646 UTC on 13 September 2018. GCOM AMSR2 Microwave (89 GHz), Convective Rain Rate and Surface Rain Rate (below) indicated that the southern and southeastern portions of the eye and eyewall had become fragmented. (VIIRS and AMSR2 imagery courtesy of William Straka, CIMSS)

In a toggle between DMSP-17 SSMIS Microwave (85 GHz) and GOES-16 Infrared Window (10.3 µm) images from the CIMSS Tropical Cyclones site (below), microwave imagery revealed the very large internal core of the hurricane at 1216 UTC.

The Metop-A satellite passed over the western edge of Florence, with ASCAT sensing surface winds as high as 66 knots along the western edge of the storm core (below).

Comparisons of Visible and Infrared Window images from Terra MODIS (1538 UTC), NOAA-20 VIIRS (1804 UTC) and Suomi NPP VIIRS (1854 UTC) are shown below.

As Florence approached the coast, it moved over Gulf Stream waters as warm as 82-85ºF, as seen in a comparison of 12 September MODIS Sea Surface Temperature product and 13 September MODIS Visible images (below).

The strong winds associated with Florence created large waves which induced upwelling of colder water from below the ocean surface:

Updated #HurricaneFlorence cold #SST wake movie, for your viewing pleasure. Created using AMSR2 satellite observations. pic.twitter.com/fofxpO8suh

— Kris Karnauskas (@OceansClimateCU) September 15, 2018

Overlapping GOES-16 (GOES-East) Mesoscale Domain Sectors were providing images every 30 seconds; “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) animations are shown below. Note that a secondary eyewall began to form following a convective burst which developed southwest of the eye around 1920 UTC (Visible | Infrared) — and as the new eyewall convection quickly wrapped around to the north, Cape Lookout, North Carolina (Buoy CLKN7) recorded a peak wind speed of 73 knots at 20 UTC and 21 UTC.

The large pattern of upper-tropospheric outflow was quite apparent on GOES-16 Near-Infrared “Cirrus” (1.37 µm) images (below) — spanning a distance of approximately 1000 miles.

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Hurricane Florence maintained Category 4 intensity on the morning of 11 September 2018 — and 1-minute (initially 30-second, until 1345 UTC) Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) and “Clean” Infrared Window (10.3 µm) images (below) showed improving eye structure after the tropical cyclone completed an eyewall replacement cycle during the preceding nighttime hours (MIMIC TC). A distinct pattern of transverse banding was also evident within the northern semicircle of Florence on Infrared imagery.

DMSP-18 SSMIS Microwave (85 GHz) imagery from the CIMSS Tropical Cyclones site (below) showed a large eye at 1015 UTC, and also at 1103 UTC.

GOES-16 Upper-level Water Vapor (6.2 µm) images with Derived Motion Winds (below) revealed that a well-defined high altitude outflow channel had developed northwest of Florence, helping the storm to maintain its intensity.

1-minute GOES-16 True Color Red-Green-Blue (RGB) images (courtesy of Kathy Strabala, CIMSS; details) are shown below. A larger-scale RGB animation beginning at sunrise is available here (courtesy of Rick Kohrs, SSEC).

Taking a closer look at the center of Florence later in the day, 1-minute GOES-16 data (below) showed mesovortices within the eye on Visible imagery, along with a narrow radial band of colder (darker red) cloud-top infrared brightness temperatures about 30-50 miles from the inner edge of the eyewall.

===== 12 September Update =====

Florence remained at Category 4 intensity early in the day as it continued its northwestward motion toward the southeast coast of the US on 12 September. A 20-hour period of 1-minute GOES-16 Infrared images (from 0000-2015 UTC) is shown below.

Nighttime toggles between VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 are shown below (courtesy of William Straka, CIMSS). Bright lightning-illuminated cloud areas can be seen on the DNB images distant to the north and northwest of the storm center; with minimal illumination from the Moon (which was in the Waxing Crescent phase, at only 10% of Full), Florence was illuminated primarily via airglow. On the Infrared images, a coarse pattern of transverse banding was evident along the far southern and western periphery of the storm.

A sequence of Terra/Aqua MODIS and Suomi NPP VIIRS Infrared images (below) showed dramatic changes in the cold central dense overcast (CDO) of Florence between 02 and 18 UTC.

During the morning hours, 1-minute GOES-16 Visible and Infrared images (below) once again displayed a distinct eye and eyewall structure, with surface mesovortices evident within the eye. A curious linear standing wave — extending radially outward to the northeast of the storm center — developed from about 13-15 UTC (best seen on Infrared images).

ASCAT surface scatterometer winds from Metop-A (below) were as strong as 76 knots just northeast of the eye at 1450 UTC.

A stereoscopic animation using GOES-16 and GOES-17 imagery is shown below — to view in three dimensions, cross your eyes until 3 equal images are apparent, then focus on the image in the center. *Note: GOES-17 images shown here are preliminary and non-operational*

During the afternoon hours, GOES-16 Visible and Infrared images (below) showed that the eye presentation  was beginning to deteriorate as Florence weakened to Category 3 intensity by 21 UTC.

The MIMIC Total Precipitable Water product (below) indicated that high TPW values associated with Florence began to move inland along the US East Coast by the end of the day.

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